Process of recovering lithium salts from phosphate minerals containing lithium



Patented July 6, 1926.

UNITED I STATES PATENT. OFFICE.

ms mm, Imn'OBT-ON-THE-m, GEBIANY, ABSIGHOB TO CORPORATION, OI NEW YORK, N. Y., A CORPORATION OF NEW YORK.

pm or noovaame LITHIUI sure no: rnosrm'ra xnmms con'rnxme mm. Application fled Iovember M, 1984, Serial No. 752,084, and in Germany December 18, me.

It is old practice to decompose silicates containing hthium for instance lepidolite etc. by means of alkali metal sulphates; .it also has been proposed to glow (calcine) I lithium-containing phosphates, e. amblygonite, in the presence of acid sogium sulhate to render the lithium water-soluble.

n both cases the finely pulverized mineral is mixed with the salt and heated to a tem- 10 perature which lies below the sintering point and consequently far below the me ting point.

It has now been foundthat neutral alkali metal sulphates are capable of uantill tatively decom ing lithium minera s containin phosp orus such as ambly onite, triph ite, etc. The new process based u n this iscovery represents a material step orward as compared with the old processes, since heating of for example potassium sulhate and amblygonite gives a readil fusible melt even at a dark red heat. The iqu'id phase of the reacting materials facilitates the decomposition as oomlpared with the solid phase involved in t e old p The heretofore necessary stelp of finely ulverizing the minerals is e minated. liquid product of reaction can be easily chilled y means of water and the lithium sulfilllat'e readily extracted.

is action of neutral alkali metal sulphates upon phosphates containing lithium could not be foreseen, although it was old practice to treat silicates in a similar manner. Phosphates and silicates are ordinarily not chemical equivalents, the composition of the two classes of minerals bein entirely difierent. The phosphates contain of the alkali group only the element lithium,

' chemically entirel whereas the silicates contain also sodium 40 or potassium or both.

The rior method of decompo lithium mineras by means of sodium disu phate .is different from the in vention. The bisn phate is used as a substitute for the sulphuric acid heretofore used andits action is essentially that of an acid whereas the invention deals with a neutral re ent.

wampZe.Equal parts of amblygonite and potassium sulphate are heated to melting temperature. The liquid product of reaction 1s then chilled with water and systematically lixiviated. The solution contaming only potassium and lithium sulphates is then furthertreated in well known manner for the production of lithium by separating out the excess of potassium sulphate by means of, fractional crystallization and precipitating from the mother liquor the lithium for instance, as carbonate. The recovery of the lithium is technically uantitative. The regenerated potassium su phate can be utilized "or a new decomposition. I claim: v

1. Process of recovering lithium salts from phos hate minerals containing lithium, whic consists in heatin the ore 1n the presence of a potassium su phate until melting is efiected and recovering lithium sulphate from the melt. j

2. In a process of recovering lithium salts from phosphate minerals containing lithium, the step w ich consists in heating the ore inthe presence of a neutral alkali metal sulphate until melting is efiected.

In testimony whereof, I aflix my signature. 1

' Du. HANS WEIDMANN. 

